Who, how, and when was the chemical formula of the dichromate ion determined to be Cr2O7-- and not HCrO4-?

Question

Most multiply-charged anions have less-charged versions stable in more acidic solutions, including the chromate ion CrO4--. However, most such anions are partially acidified simply by adding one or more hydrogen atoms to them, such as HCO3-, HPO4-- and H2PO4-, HSO4-, and so on. The partially acidified chromate ion is different in this respect, where two of the basic Cr2O4-- ions combine to form a Cr2O7-- ion rather than two HCrO4- ions implied by the older name for the dichromate ion "bichromate." Who, when, and how was this anomalous behavior discovered and what chemical consequences does it have?

I am also looking for references for more detailed info. These must be provided for "best answer."

Answer 1

Acidify a sample of potassium chromate and devaporate to dryness. Potassium dichromate will result K2Cr2O7.

In neutral or alkaline solution, the crytsals that will form are the original postassium chromate.

Analysis of the chromium content (27% K2CrO4 vs 35% K2Cr2O7) will yield the emprical formula.

Sorry, I can't help with the history.

Answer 2

Mg(OH)2 is the terrific suited chemical formulation because of the fact it takes 2 Hydroxide ions to bond with Magnesium oftentimes it may be written with a subscript quantity 2 somewhat than the parenthesis and quantity 2

Answer 3

I have no idea when this was discovered. The formation of Cr2O7= from CrO4= follows a reaction of the form:
2 CrO4= + 2H+ -> H2O + O3-Cr-O-Cr-O3 =
Clearly you need acidic surroundings to form the dichromate ion.

Answer 4

Formula Of Dichromate Ion